One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,5)(4,7)(6,8)(9,10)(11,17)(12,16)(13,14)(15,19)(18,23)(20,21)(22,24)(25,26)(27,35)(28,37)(29,34)(30,32)(31,38)(33,39)(36,40) involution — undirected(2,3)(6,7)(10,14)(15,17)(16,21)(22,23)(25,27,30,38)(26,31,32,35)(28,34,39,36)(29,37,40,33)(1,2,5,3)(4,6,8,7)(12,20)(16,21)(18,24)(22,23)(26,32)(29,40)(31,35)(33,37)(1,3,5,2)(4,7,8,6)(9,11)(10,15)(12,18)(13,19)(14,17)(16,22)(20,24)(21,23)(25,27)(26,31)(28,36)(29,37)(30,38)(32,35)(33,40)(34,39)(1,4)(2,6)(3,7)(5,8)(9,10)(11,15)(12,16)(13,14)(17,19)(18,22)(20,21)(23,24)(25,28,30,39)(26,33,32,37)(27,36,38,34)(29,31,40,35)(9,12)(10,16)(11,18)(13,20)(14,21)(15,22)(17,23)(19,24)(25,29,30,40)(26,34,32,36)(27,37,38,33)(28,31,39,35)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.